Boston and Cambridge drivers, pedestrians, and cyclists got a holiday gift from the state last week, when major work finished on the Boston University Bridge after 2 1/2 years and $19 million in construction costs.

I stopped by the span formerly known as the Cottage Farm Bridge (pre-1949) on Thursday, when the LivableStreets Alliance was out celebrating the completion by handing out baked goods and asking passersby to sign postcards. The advocacy group wanted to thank the state Department of Transportation for considering the needs of walkers, bicyclists, and people with disabilities as well as drivers in reconstructing the bridge, which dates to 1928.

When state engineers first contemplated the project, they planned merely to rehabilitate the rusting, crumbling bridge with the same configuration it had known for ages: two tight lanes of traffic in each direction, no shoulder or dedicated space for bicyclists, and a harrowing series of lane hops and tiny islands for pedestrians on the Cambridge and Boston approaches.

But officials reconsidered and ultimately redesigned the bridge to hold three lanes of traffic - one in each direction on the approach switching to two on the exits, intended to accommodate through and turning traffic while giving more space to cyclists and walkers. They also improved the approaches with an eye to pedestrian safety.

“It has been so long in coming,’’ said Elizabeth Reed of Jamaica Plain, an MIT dean who has been biking to and from her Cambridge office for more than 30 years. She stopped to sign a postcard for MassDOT, one of about 125 LivableStreets collected, happy to thank them for improving what had long been the most harrowing part of her commute. “It’s taken a long time, but I think it will be really worth it.’’

The work on the BU Bridge was the first to begin in a coordinated eight-year, $400 million-plus state effort to rehabilitate or replace six major Charles River bridges linking Boston and Cambridge. Two of those six are done now. (The Craigie Bridge-Craigie Drawbridge began after BU but was completed first.)

MassDOT spokeswoman Cyndi Roy said some minor work remains on the BU Bridge, with “punch list’’ items to be finished this week and landscaping to follow in the spring. The state will monitor traffic for four months to determine if any changes are necessary, she said.

In other bridge news, the state will hold a ribbon cutting Tuesday to celebrate the completed Winter Street Bridge over Route 128 in Waltham, a $23 million project to rebuild that bridge and expand the Exit 27 interchange. That project, separate from the Accelerated Bridge Program, began in 2005 but stalled after the first contractor collapsed in the economic downturn.

Boston Meter Cards work well — just not for Massport’s spaces

I’ve written twice recently about the prepaid Boston Meter Card, once to report its introduction and again to check a tip that card use would rapidly drain batteries on the 7,200 meters that accept them (erroneous, according to the Boston Transportation Department).

Now, entry number three: An employee at a Seaport District hotel e-mailed to say how excited he and his co-workers were to learn about the cards, given their continual hunt for quarters as they meter-hop to avoid nearby lots and garages, which range from $13 to $30 a day.

Then the employee discovered, to his frustration, that the meters near his hotel did not accept the prepaid cards.

“The meters look to be the same exact ones that the city has elsewhere,’’ wrote the employee, who asked not to be named in print because of his hotel’s corporate policy. “Ironic that as you leave the Seaport area heading towards South Station on Summer Street there is (or was) an electronic signboard advertising the cards!’’

I asked the BTD about this, given that they had said the cards would work at all of Boston’s meters except for the 107 multispace meters that serve 1,000 spaces on or near Newbury Street (those are the meters that accept credit cards and print out window-sticker receipts) and the 144 downtown meters that are part of a free pilot program to test credit card-reader technology at single-space meters. In other words, if you see a meter that is not newfangled, it should take the parking cards.

Turns out BTD meant only at their meters, and there are a limited number of parking meters in the city not overseen directly by City Hall. And nearly all of those are along the now-bustling South Boston waterfront.

The Massachusetts Port Authority has 131 meters in that area, spread across Northern Avenue, Seaport Boulevard, Congress Street, D Street, and Harborview Lane, according to Massport spokesman Matthew Brelis. And the Boston Redevelopment Authority has a handful of multispace meters on special economic-development property near Drydock Avenue, by the Boston Design Center and Black Falcon Cruise Terminal. Both are outside BTD’s purview. (To make it both more - and less - confusing, no multispace meters accept the card, anyway, offering the alternate convenience of accepting credit cards.)

The good news, for the hotel employees, is that the city does have 243 Boston Meter Card-accepting meters of its own in the Seaport District: 132 on Seaport Boulevard (between Seaport Lane and East Service Road), 27 along Boston Wharf Road, 21 on East Service Road, 25 on Congress Street (B Street to Boston Wharf Road), and 38 along Northern Avenue.

Massport has no plans to accept the meter cards - those prepaid funds go to the city - but the quasipublic state agency does at least operate its meters on the same hours as Boston these days, a change that occurred in 2007, after complaints from drivers perplexed by Sunday and holiday tickets.

Through Friday morning, Boston had sold 2,021 meter cards, or about 500 a week. The cards, discounted 20 percent until New Year’s, are available at City Hall, the Boston Tow Lot, and at cityofboston.gov/transportation.

State’s rules about when it’s OK to make U-turns murky at best

Allan Goldstein has been driving a Boston taxi for more than 40 years. In that time, he has made thousands of U-turns, many of them on North Street at Union Street, near Faneuil Hall. For the first time recently, Goldstein was pulled over and cited for that move.

“[I’ve] been taking that U-turn many times in my 40-year career even with police cars behind me, but this time there were motorcycle cops sitting there and even then I thought it would be OK,’’ Goldstein e-mailed, wondering if he was fairly cited. “P.S. 5,000 Boston cabdrivers are waiting for feedback.’’

The intersection in question is prime turf for taxi drivers, awash with tourists, business types, and bar hoppers. North Street runs from City Hall to the Rose Fitzgerald Kennedy Greenway; Union Street is the block flanked by the New England Holocaust Memorial and the restaurant row that includes the Union Oyster House.

Goldstein said he makes U-turns there and not a block east at North and Clinton streets (by the Hard Rock Cafe and Millennium Bostonian Hotel) because a sign at that intersection expressly prohibits them.

So I asked the Boston Transportation Department if U-turns were legal here, or for that matter anywhere lacking a no-U-turn sign. They directed me to the Boston Police Department, where spokeswoman Elaine Driscoll addressed U-turns generally without commenting on the specific case.

Police and state law treat them similarly to left or right turns, meaning they are legal unless specifically prohibited by signs, though officers can use their discretion about the safety of crossing center lines.

“If the driver has concerns about his ticket, I would encourage [him] to take advantage of the appeals process,’’ Driscoll said in an e-mail.

Massachusetts General Laws do not mention U-turns, much less define them. The 168-page official state Driver’s Manual, revised in September, says you can make a U-turn from the lane closest to the center line “if your path is clear and it is safe to do so. You cannot make make a U-turn if a NO U-TURN sign is posted.’’ It also says to avoid U-turns at the crest of a hill, near a curve, or if you lack a 500-foot view of oncoming traffic - but doesn’t say if that’s the law or just a good idea.

The three-way intersection where Goldstein was cited has an unbroken double-yellow line. The RMV manual says nothing about U-turns over double yellows while warning that you may cross them to turn left only “when it is safe to do so.’’

Peter DeMarco addressed this scenario last year in his “Who taught you to drive?’’ column in the Globe’s regional editions. At the time, RMV chief of staff Erin Deveney said a U-turn over a double yellow is legal if there is no oncoming traffic and no sign prohibiting it. But multiple law enforcement and driver’s-ed sources gave varying answers.